Sugar beet flowering is controlled by a cold weather treatment of the plants known as vernalization followed by days of long, uninterrupted periods of light known as long days. As the days lengthen, the beets produce bolters which are elongated stems bearing flowers which ultimately produce seeds of indeterminate, multibranched racemes. In Europe where large acreages of sugar beet are grown, cold spring weather following spring sowing is often enough to induce bolting of the beets. This bolting causes various problems to the farmer who grows the beet for the sugar content of the beet root. One problem is that bolting reduces both the size and the sugar content of the beet root since the products of photosynthesis are diverted to flower production. Another problem is that bolting causes processing difficulties due to lignification of the root, since the presence of lignin reduced the efficiency with which sugars can be extracted. Bolters also physically interfere with mechanical harvesting by becoming entangled in harvesting machinery. Another problem is that bolted plants cause a large amount of competition by shading adjacent plants, thereby reducing their root size. With time, the seed from early bolters produce a weed beet with an annual habit requiring little or no vernalization. This weed beet, besides causing severe competition, prevents "beet-free periods" which are necessary for the control of beet yellowing virus.
If bolting could be completely prevented, this would be a possible means of realizing the potential physiological advantages of autumn sowing. Greater utilization of the season would be achieved by the capturing of radiation which normally falls on bare ground. Yield increases of up to 25 percent have been predicted from autumn as opposed to spring sowing. Clearly, there is a need for compounds which can control and/or prevent bolting in sugar beets.